Temperature dependence of associative equilibria of DMSO according to raman scattering spectra

Raman scattering spectra of dimethyl sulfoxide (DMSO) are studied in the area of the line corresponding to symmetric CSC stretching vibrations of the molecule. It is established that this line is composed of a low-frequency component that corresponds to the vibrations of monomeric molecules and a high-frequency component that corresponds to the vibrations of DMSO dimers. Values of self-association equilibrium constants K _a varying in range from 0.20 (23°C) to 0.081 (100°C) are obtained. Since the intensities of the respective components of the line contour are proportional to the compound’s concentrations, the enthalpy of DMSO self-association (ΔH = ?11.7 ± 0.9 kJ/mol) is determined from the temperature dependences.     

On the Reasons of Assymetricity of the Shape of Contour of Vibrational Line ν1(A 1) in Raman Spectra of LiNO3 Melt

Optics and Spectroscopy - The reasons leading to the asymmetry of the shape of the ν1(А1) contour of the nitrate ion in the spectra of lithium nitrate melts were analyzed. It was shown...     

Anomalous temperature dependence of interfacial tension in water-hydrocarbon mixtures

An experimental study of the interfacial tension (IFT) as a function of temperature for three water-hydrocarbon mixtures is reported. The interfacial tension rises with increasing temperature for all mixtures studied, which contradicts the Antonov rule.     

Effect of surface-active additives on the temperature behavior of interfacial tension in water-<Emphasis Type="Italic">n</Emphasis>-hexane systems

The temperature dependence of interface tension in a water-n-hexane system without additives and after addition of stearic acid was experimentally studied at four different concentrations. A method for determining the excess surface chemical potential from experimental data on the temperature dependence of interfacial or surface tension is proposed for a diluted solution of surface-active impurity. The excess surface chemical potential of stearic acid at the interface of a water-n-hexane binary mixture is determined.     

Vibrational spectra of an LiNO3–(CH3)2SO2 system

Raman and IR absorption spectra were studied and molecular relaxation characteristics of vibrations of the anion and solvent were calculated for an xLiNO₃–(1 – x)(CH₃)₂SO₂ system (x = 0.1, 0.2, 0.3, 0.4 M). It was found that it is impossible to increase the concentration of free ions involved in charge transfer in such a system by either increasing the temperature or changing the concentration composition in the studied range of x.